Patent GB-827595-A (GB)
Title: Improvements in and relating to oil burner control systems
Inventor: DONALDSON ALEXANDER JOHN
IPC: F23N5/22
Filed: 1955-09-05
Abstract: 827,595. Controlling burners. KINGSBURY COMPONENTS Ltd., and DE ROEMER, A. H. Sept. 4, 1956 [Sept. 5, 1955; March 14, 1956], Nos. 25457/55 and 8022/56. Class 75(1) An oil burner control system. Fig. 1, comprises starting contacts TMST, burner motor contacts TMMR, lock-out contacts TMLO and running contacts TMRN all controlled by a timing motor TM, first and second relays R/2, S/3. a flame switch FS. one set of contacts Rl of the first relay R/2 being in series with the first relay R/2 and being bridged by the starting contacts TMST whereby the first relay can be operated initially only when the timing motor is in the starting position, the second relay S/3 being operated upon operation of the burner motor contacts TMMR and adapted to start the burner motor BM, the burner motor contacts TMMR being released after a predetermined interval and the second relay S/3 being then maintained operated through the flame switch FS in its "hot" setting, the lock-out contacts TMLO being operated or put in a condition to be operated by the timing motor for only a small part of the cycle of operation of the timing motor and being adapted when operated if the flame switch is in its "cold" setting to stop the timing motor, the latter being incapable of restarting without a manual operation. Ir operation, on closing a mair switch MS the front relay R/2 is energized through the lockout contacts TMLO the back contacts of an oil thermostat OTH, the back contacts of th( starting switch TMST and th( contacts of a main thermostat THB. The relay closes contacts R1 which short-circuit the starter switch TMST and the oil thermostat OTH, and the contacts R2 which energize the timing motor TM. After a few seconds the timing motor TM operates the starting switch TMST and after a further few seconds the timing motor TM closes ignition contacts TMIG to energize an ignition transformer ID, and shortly after this the timing motor TM closes theburner motor contacts TMMR to energize the second relay S/3 which closes contacts S1 to energize the burner motor BM. The relay S/3 also closes contacts S3 connecting it to the hot contact of the flame switch FS, and the forward contacts of a switch S2 so that the timing motor is supplied through the closed running contacts TMRN. Forty seconds later, by which time the flame switch FS will have moved to its hot setting if ignition has been successful, the motor opens the ignition contacts TMIG and the burner motor contacts TMMR. The relay S-3 is now energized through the hot contact of the flame switch FS. The timing motor continues to rotate and two seconds after the opening of the ignition and burner motor contacts the lock-out contacts TMLO are for a short time put in condition to open but are further controlled by a mechanical interlock controlled by the first and second relays R/2, S/3 in such manner that if the first relay R/2 is de-energized before or simultaneously with the second relay S/3 lockout cannot occur but if the relay S/3 only is de-energized lock-out occurs. If lock-out does not occur the timing motor continues to operate until it opens the running contacts TMRN. This is the normal burner operating position. If flame failure occurs during normal burner operation the relay S/3 is de-energized by the flame switch FS and the timing motor TM is again energized through contacts R1 the cold setting of the flame switch FS and the contacts R2 and after three seconds the running contacts TMRN close and after two minutes to allow for dispersal of accumulation of fuel the contacts TMST return to the starting position and the starting cycle is carried out. If the demand for heat ceases the main thermostat THB opens releasing the first relay R/2 and thereby the second relay S/3. The timing motor TM is again energized through the oil thermostat OTH, the contacts TMST and the back contacts of the switch S2 and operates to bring the system to the starting condition; the starting cycle is then carried out- In the event of power supply failure the first and second relays R/2, S/3 are released and when the power is restored the timing motor is again energized through the oil thermostat OTH, the contacts TMST and the back contacts of the switch S2. The system is thus brought to the starting condition and the starting cycle is then carried out. If during the starting cycle the burner fails to ignite the flame switch does not move to the hot setting and consequently the relay S/3 is deenergized when the timing motor opens the ignition contacts TMIG and the burner motor contacts TMMR. The first relay R/2 remains energized however and accordingly the mechanical interlock does not prevent the lock-out contacts TMLO from opening when put in the opening condition by the timing motor TM. The timing motor therefore stops and can only be restarted by manually resetting the lock-out contacts TMLO. The timing motor is then energized through the oil thermostat OTH, the contacts TMST and the back contacts of the switch S2. The system is then brought to the starting condition and the starting cycle is carried out. The mechanical interlock is shown in Fig. 2 and comprises a bar 10 pivoted at 11 and bearing through a roller 12 on a cam 13 driven by the timing motor TM and having a depression 19 which allows the roller to fall, thus opening a micro-switch 9 constituting the lock-out contacts TMLO. The first relay R/2 has a spring returned armature 14 having a hooked end adapted, on deenergization of the relay, to engage a hook 18 on the bar 10 and thereby prevent the bar from pivoting. The second relay S/3 when energized moves a block 17 in the direction of the arrow and prevents the bar from pivoting. If both relays are deenergized simultaneously the hooked end of the armature 14 engages the hook 18 and thus prevents the bar from pivoting so that lock-out is prevented. If relay S/3 is de-energized and relay R/2 is not deenergized until the roller 12 has at least partly intered the depression 19 lock-out can occur. The oil is heated by a heater OH energized by contacts C1 of a contactor C/1 energized by the oil thermostat OTH. The circuit also includes a starter overload switch SO, a time switch TS, a thermostat EOT adapted to open its contacts when the oil temperature is excessive and a warning lamp WL energized by the overload switch SO or by the lockout contacts TMLO. In the modified circuit shown, at starting relay R/3 is energized through the oil thermostat OTH, the starting switch TMST and the main thermostat THB as in Fig. 1. The timing motor TM is then energized through contacts R1, R2, the flame switch FS in its cold setting, the lock-out contacts TMLO, and contacts R3. Cam switches TMIG and TMMR are closed in succession to energize the ignition transformer and the relay S/2 which starts the burner motor BM. The cam switch TMRN closes soon after cam switch TMMR. If ignition occurs the flame switch FS moves to its hot setting and a circuit for the timing motor is established through the flame switch FS and the cam switch TMRN. If the flame is not established the timing motor TM remains energized through the lock-out contacts TMLD and therefore stops when the contacts are opened by a notch H in the operating cam. The system remains in lock-out condition until the switch SO is manually pressed to release the relay R/3. When pressure on the switch is released the timing motor TM is energized again through the oil thermostat OTH, the timing switch TMST and the back contacts of contacts R3. A fuel valve is actuated by a cam operated switch TMB.